In the middle of redoing our bathroom and the old pipe had a 110mm admittance valve connected to the soil pipe under the bath that everything ran in to, now the pipe has been relocated to beside the toilet and is all under the floor, the question is do I need to replace the old valve with the same type or can I use a smaller type that connects to the bath or sink waste outlet?
Is that the only real option? using a like for like replacement would require running new 110mm soil pipe about 3 meters just to hide it under the new bath Is there no regs that require it to be higher than everything else?
From how I read your first post the soil pipe needs venting with a air ammitance valve,vents on the smaller waste pipes won't be enough. Remember there was a reason one was there before.
Ah so the smaller 40mm won't gave enough air flow This is how it is now, so can I just replace the 90d bend with a tee branch so the pipe can run both ways and put a 90d at the other end then the vent on top
I can't imagine why there would be a 4" AAV under your bath. Obviously I'm a bit short of information but you're quite right in saying that it should be higher than everything else. Something in the back of my mind is saying it should be a meter higher that the WC. Is there any other vent poking out of the roof or is there another AAV in the loft?
There are no others in the house, house is only a few years old and the one that was under the bath was about 200mm off the floor at the top of a branch that the old bath and toilet ran in to.
it needs to be above the highest water level, normally the basin. you can meet the regs by using a 3" valve but they are not much smaller tbh.
Thats the same thing as the highest water level ;-) if they are install below they have the potential to fail and you have an insurance claim that will be rejected due to poor workmanship.
I have a couple of question re venting/AA Valves. Hoping someone can help. Would I be right in thinking that an AA valve is not the right thing for venting soil pipe/septic tank fumes? Would that need to be an 'open' vent? If I need to use open pipe, then I have a bit of a problem with positioning because of prevailing winds. Second, I have a toilet which suffers from' back syphoning.' I am thinking that an AA valve is the answer. The soil pipe does not extend above the toilet and is not be possible to fit one. Does it matter where along the soil pipe it would be fitted ie closer to the septic tank?. It cannot be accessed for several metres. Is fitting a valve to the basin pipe of any use ( if they share the same outlet. Not sure if they do)
Vent pipes are only required by NHBC on the end of a drain run in any row of dwellings, if your toilet is syphoning out it is due to negative pressure. A sucking force generated by a plug of water moving down the line, fit an AAV as close as possible to the pan & an anti vac trap on basin
I saw an air admittance valve cause some serious damage when installed in a void behind a stud wall. It was installed too low, below that of the pans (pub bog). After a blockage down stream, it obviously backed up and over, and filled the void with sh1te. They had pest control in as they kept saying they could smell dead rats. I opened the wall from the other side for a completely different job and was met with a disgusting site! They then realised it wasn't a rat smell.....
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